Rabbenu Gershom ben Yehuda

(c.960 - 1028)

From around 220 CE until the tenth century, the major center of Jewish learning and authority
was Babylonia. The great academies
there developed the arguments we now call the Talmud.
The leaders of these academies answered Jewish questions from around
the world for centuries.

By the middle of the tenth century, however, the authority
that the Babylonian Jewish Academics had held over the other Jewish
communities had begun to diminish.

Rabbis had
established their own legal schools in Spain, North Africa, and Germany.
For a while, these new Jewish centers relied on the responsa from the
geonim (plural of gaon; the Jewish authority) of Babylonia.

Gradually, however, the differences in lifestyle and
the distance from Babylonia to Spain and Germany encouraged the
heads of the German and Spanish legal academies to issue their own authoritative
decisions. These became binding on their communities and marked the
beginning of the end of the period of the Babylonian Geonate. Babylonia's
academies lost their authority over the rest of the Jewish world.

The most obvious split between the Babylonian academies
and the German academy in Mainz took place at the beginning of the eleventh
century. The leading German rabbi was Gershom, known by German Jewry
as Rabbenu Gershom (our Rabbi, Gershom). According to tradition, Rabbenu
Gershom wrote four special ordinances which differed with Babylonian Halachah (and Spanish Halachah, for that matter).

First,
Rabbenu Gershom declared that a man could have only one wife at a time.
This ruling was revolutionary. According to the Mishnah and the Talmud, a
man could have four wives at the same time (provided he could keep them
fed, clothed, and sexually satisfied). This law continued in both Babylonia and Spain, where Muslim law definitively forbade bigamy, Rabbenu Gershom decreed that only one
wife was permitted. This law became binding for all Ashkenazic Jews and established a major cultural split between Sephardic and Ashkenazic Jewry.

In
addition, Rabbenu Gershom decreed that a women had to agree to a divorce before a man could give her a get. He also made it a major sin
to open and read someone else's mail, thus ensuring the privacy and
safety of mercantile transactions between Jewish communities.

Finally, Rabbenu Gershom forbade Jews to remind a Jew
forced to convert to Christianity of his previous shame.

Modern scholars challenge whether all these ordinances
were actually decreed by Rabbenu Gershom. However, they so clearly marked
a change in German Jewry's reliance on Babylonia that they remain significant.